For various medical reasons, such as diagnostic tests or the like, it is often necessary for a physician to obtain a tissue sample of a patient's body. Often, tissue sample is required for diagnostic purposes from a soft tissue, such as breast tissue as opposed to a biopsy from a more rigid structure, such as bone marrow. Soft tissue specimens generally contain a less rigid structure and are easily deformable as opposed to bone marrow structures which are generally recovered with significant portions of their internal bony trabecular structure intact.
One exemplary surgical instrument for the severing and/or retrieval of biopsy specimens is disclosed in U.S. Pat. Nos. 5,522,398; 5,843,001; and 6,015,391, of which the present applicant is also inventor. Each of these patents is hereby expressly incorporated herein by reference. While these instruments are particularly suited for severing and collecting a more rigid tissue specimen, such as a bone marrow specimen, the instruments are not as effective at severing and/or retaining soft tissue samples. In addition, the concept of recovering a specimen by pushing it toward the handle from the tip of the needle may not be as applicable for soft tissue specimens as it is for bone marrow specimens. An attempt to push the specimen through the needle can result in disruption of the specimen because soft tissue specimens have less structure. Moreover in a long needle, such as an endoscopic SNARECOIL (trademark) needle, the length of the needle would be prohibitive in successfully transferring the specimen from the distal aspect of the needle through the length of the needle and out of the proximal end of the needle.
In addition, U.S. patent application publication Nos. 2005/0054948 and 2005/0054947, filed by the present applicant, disclose soft tissue biopsy needle designs. The '948 publication and the '947 publication disclose designs which incorporate a dual spring-loaded mechanism. A high force spring is used to project the needle forward and initiate the biopsy cycle. As the snarecoil needle is projected forward, a second mechanism is activated which releases the force of the second spring which activates the snarecoil through a pin/groove mechanism. The publication also discloses seal mechanisms that are designed to help generate a negative intraluminal pressure as a needle projects forward in order to “draw” the specimen into the needle lumen as the needle cuts the specimen.
The '947 publication discloses a needle that rotates as it advances to increase the cutting efficiency of the needle tip and also incorporates a dual spring mechanism for activating the snarecoil at the end of the biopsy cycle. The design includes an assembly that maintains the alignment of the inner and outer needle tubes during advancement and rotation of the needle and allows the inner tube to rotate relative to the outer tube at the end of the biopsy cycle to facilitate snarecoil activation.
While the above designs are suitable for their intended uses, there is a desire to provide a simpler design that incorporates less mechanical components that translate into a number of advantages over the above designs.
Other conventional procedures and instruments used for obtaining the samples, while not overly complex, almost universally result in excessive patient discomfort and often overly extends the patient's and operator's time and budget.